(1) Field of the Invention
The present invention relates to a cleaning apparatus for removing toner remaining on a charge image retentive member such as photosensitive member.
(2) Related Art Statement
Image forming machines such as a printer system or a copying maching have been practically used which form a reproduction image on the charge image retentive member such as photosensitive member or insulating dielectric film through the formation of electrostatic latent images. According to such image forming machines, the electrostatic latent image formed on the charge image retentive member is converted to a toner image by means of a developing unit and the toner image thus obtained is transferred onto a receiving medium such as a plain paper to form a visible image. On the other hand, toner remaining on the charge image retentive member after the transferring is removed by a cleaning apparatus, and then an electrostatic latent image is formed on the cleaned charge image retentive member again, thereby enabling repeated formation of images. However, the toner image cannot be completely transferred onto the recording medium in the image forming machine, development of cleaning apparatuses which can effectively remove the residual toner remaining on the charge image retentive member after transferring have been strongly demanded.
Japanese patent publication No. 50,34,340 describes a cleaner unit for removing the toner remaining on the charge image retentive member. As shown in FIG. 5, this cleaner unit comprises a plate-like cleaning blade 1 made of a rubbery elastic material. A support holder supports a base portion of the cleaning blade 1 and pushes it against a photosensitive member such that the blade is curved in a direction in which the blade approaches the photosensitive member. Thereby, an edge of the blade is press contacted upon the surface of the photosensitive member by utilizing a resilient restoring force originating from the curving of the blade. When a frictional force of the running photosensitive member and a push force of the residual toner act upon the edge portion, the blade is further curved to approach the photosensitive member and the residual toner is removed by utilizing the resilient deflection due to the curving of the blade.
In the known cleaner unit mentioned above, it must be that the plate-like elastic rubber blade is pushed against the photosensitive member such that the central portion of the blade is curved to approach the photosensitive member and the edge portion is press contacted with the surface of the photosensitive member by utilizing the resilient restoring force caused by this curving and that an acting direction of a composed force between the press contact force and the frictional force is accurately coincided with the longitudinal direction of the curved blade. For this reason, when the blade is to be set, a press contact angle and a curved amount of the blade must be accurately determined relative to the photosensitive member. Consequently, the blade-setting operation unfavorably becomes troublesome.
Further, as the frictional force acts upon the blade, the blade functions to bite the running photosensitive member, with the result that the edge portion of the blade is more strongly press contacted with the photosensitive member. Accordingly, damages upon the photosensitive member becomes greater and its use life becomes shorter due to abrasion of the photosensitive member. Owing to this, a release mechanism must be provided to free the press contact, when the system is stopped, for preventing damages upon the photosensitive member and the abrasion of the blade itself. This causes the inconvenience that the structure of the cleaner unit becomes complicated.